Cardiac warning device

ABSTRACT

A method and apparatus for detecting and responding to herald signs in the cardiac waveform, such as a fast heartbeat rate, a low rate or a skipped heartbeat. In one embodiment the detection of a herald sign causes the ECG waveform to be transmitted to a remote location where it is analyzed and a signal retransmitted to the patient triggering an alarm or causing other appropriate action. In another embodiment, the detection of a herald sign causes the ECG to be recorded on a loop of magnetic tape or a modular solid state memory device in the unit so that the tape can be replayed and acoustically coupled to the telephone line after the patient calls the central facility. In yet another embodiment, the detection of different herald signs causes different alarm signals, e.g., colored lights, different alarm signals identifying the abnormality, to be operated to indicate to the patient what medication he should administer to himself or whatever other action he should take in the event that communication with central facility cannot be immediately achieved.

United States Patent [1 1 Unger [54] CARDIAC WARNING DEVICE [76]Inventor: Paul N. Unger, 945 Arthur Godfrey Road, Miami Beach, Fla.33140 [22] Filed: June 2, 1970 [21] Appl. No.: 42,850

[52] US. Cl. ..l28/2.06 A, 128/419 D [51] Int. Cl. ..A6lb 5/04 [58]Field of Search ..128/2.05 R, 2.05 S, 2.05 T,

128/2.06 A, 2.06 F, 2.06 G, 2.06 R, 2.1 A,

[56] References Cited UNITED STATES PATENTS 3,650,263 3/1972 Kavalski etal. ..128/2.06 A 3,144,019 8/1964 Haber ....l28/2.06 A 2,848,992 8/1958Pigeon ..l28/2.06 F 3,426,150 2/1969 Tygart ....128/2.06 R 3,221,33411/1965 Jones, Jr ....l28/2.06 G 3,212,496 10/1965 Preston 1 28/2.06 R3,513,833 5/1970 Finch et al........ ....128/2.06 R 3,318,303 5/1967Hammacher..... .....l28/2.05 S 3,460,542 8/1969 Gemmer ....128/2.06 A3,434,151 3/1969 Bader et al.... ....128/2.06 R 3,236,239 2/1966Berkovits ....128/2.05 R 3,572,316 3/1971 Vogelman et al ..l28/2.05 R

[4 1 Apr. 3, 1973 Primary Examiner-William E. Kamm Attorney-Cushman,Darby & Cushman [57] ABSTRACT A method and apparatus for detecting andresponding to herald signs in the cardiac wavefonn, such as a fastheartbeat rate, a low rate or a skipped heartbeat. In one embodiment thedetection of a herald sign causes the ECG waveform to be transmitted toa remote location where it is analyzed and a signal retransmitted to thepatient triggering an alarm or causing other appropriate action. Inanother embodiment, the detection of a herald sign causes the ECG to berecorded on a loop of magnetic tape or a modular solid state memorydevice in the unit so that the tape can be replayed and acousticallycoupled to the telephone line after the patient calls the centralfacility. In yet another embodiment, the detection of different heraldsigns causes different alarm signals, e.g., colored lights, differentalarm signals identifying the abnormality, to be operated to indicate tothe patient what medication he should administer to himself or whateverother action he should take in the event that communication with centralfacility cannot be immediately achieved.

10 Claims, 4 Drawing Figures f T T l 24 u/v/r I l L h If I 25,4! .99 r-1-" 1 Ma/v/raz I f 1 1 i I? t I l I I J C 1 I l a m 5 1 /*z4A/JM/rr,6 il Biff/V 8 5 l I T l E i l FE/FF/ae/um g R :45 l 1 I Wane-72' IJOV/Lkjf' I I E 1 l mw/vs/wrxzz I l A e E 44 A l L y L l l 2 4% I IMflgi/efdfi g I 1 M 1 ,elxw'aur M I l 1 43 4 4 I CARDIAC WARNING DEVICEBRIEF DESCRIPTION OF THE PRIOR ART AND SUMMARY OF THE INVENTION Thisinvention is described in Document Disclosure Number 001756 filed Apr.11, 1970.

The invention relates to a method and apparatus for detectingpremonitory signs of cardiac attacks and transmitting the detectingsigns to a central location.

Almost all, if not all serious or potentially serious cardiac attacksare prefaced by warning or patient unrecognizable herald signs in theECG wave which occur in many patients long before recognizable symptomsbecome manifest. A number of such signs have been discovered and theseinclude reduction in the heart rate below a low selected rate limit,e.g., 54 and an increase above a high selected limited rate, e.g.,120-130, premature heart beats, failure to discharge an impulse, failureof an electrical impulse to be conducted from the upper to the lowerchambers, widening of the QRS complex, base line shift depression orelevation, and abrupt ST deviation.

While all of these signs do not always indicate a cardiac attack isimminent, their occurrence, particularly in individuals with previouscardiac difficulties or established potential cardiacs, is seriousenough to warrant careful study by an expert and, following recognition,institution of precautionary measures, such as indicated treatment withdrugs. For some signs, for example, when the rate slows below about 50,action should be taken immediately. However, inasmuch as many of thesigns do not normally cause distress or perceptible physical symptoms,they may pass unnoticed or even if noticed their import may not be fullyappreciated or may be rationalized away.

The present invention relates to a novel method and apparatus whereby anumber of individuals known to be cardiacs or potential cardiacs areeach equipped with a portable unit which they carry on or with theirperson and which constantly monitors the ECG wave for herald signs.

In one embodiment of this invention, the detection of a herald sign bythe unit causes the ECG to be transmitted to a central facility where ittriggers a programmed signal in a central computer in addition to thatgenerated in the unit. The ECG wave received at the central facility isthen analyzed, preferably by a digital, single purpose computer whichthen generates an output based on a programmed input which a humanexpert can then study, preferably after transmission by magnetic tapevia dataphone or similar device onto a receiving screen or other ECGdisplay. If the expert considers that the detected signs warrantprecautionary measures, he after identifying by coded number the patientand physician, directs the activation of a transmitter which sends asignal to the unit transmitting the ECG waves, triggering an audiosignal to the patient. He simultaneously communicates with the patientsphysician, advising him of the event of the identified patient. Thismaintains the patient-personal physician relationship withoutinterposing the interpreter as a patient identifiable consultant, butretaining his identity as a physician consultant.

This alarm within the patient unit indicates to the individual that heshould contact his own physician immediately for instructions, or, ifthat proves impossible,

the central facility. At the same time that the expert directedactivation of the alarm transmitter, he also alerted the personalphysician to the situation. He can also transmit to the personalphysician, via a telephone transmitter or similar device, the actual ECGwhich the computer has processed and presented to him. The alarm signalmay also indicate to the patient what self medication should beadministered, e.g., by the color of a light lit by the signal as a failsafe device in the event 0 of any breakdown in communication such asinability to reach computer monitor facility and/or his physician. Thedetection of a herald sign by the unit may also cause the alarm to beactivated if desired.

One of the advantages of this arrangement is that the logic in eachpersonal unit need not make sophisticated decisions as to whether adetected sign warrants precautions; those decisions are made by thecomputer and ultimately evaluated by a human expert. Ac-' cordingly, thelogic in each unit can be made fairly simple, responding only to a fewsimple conditions which always occur when a herald sign exists. Thispermits the unit to be made relatively inexpensively and small enough tobe easily carried by the patient. Another advantage is that the patientis not bothered by periodic false alarms which breed anxiety and causeloss of sleep. The patients alarm operates only when a potentiallyserious consideration exists which warrants further study and which hehas been taught is an early warning signal which may warrant preventiveprotective actions.

In another embodiment of the invention each unit includes an endlessloop of magnetic tape or a solid state memory device on which the ECGwave can be continuously recorded and when the logic network in the unitdetermines that a herald sign is occurring permits playback and preventserasure. Alternately the ECG waveform is recorded on the tape where itis used only after the event has occurred. Alternately, a solid statememory device permits continuous recording with modularity in choice ofplayback time with 10 seconds deemed adequate to meet the overwhelmingmajority of events and 30 seconds virtually all events. It has beenfound that the waveform after the event almost always indicates theherald sign which caused the alarm to be given.

The logic also triggers an audio alarm in the unit which indicates tothe individual that he should go to the nearest telephone and call thecentral facility. One or more visual signals can be also given bydifferent colored signals to inform the individual as to which medicineshould be self-administered where particular hazard exists andcommunication cannot be immediately established. When the telephoneconnection has been made, the magnetic tape or solid state memory deviceis played back while linked to the telephone by a conventional orminiaturized acoustic coupler and the recorded ECG thus transmitted tothe central facility. The received signals are then processed by asingle purpose properly programmed computer simultaneously displayed ona screen and continuously recorded on tape and transmitted to a humanexpert who then studies the output and determines what actions should betaken. Instructions can then be immediately given to the individualsphysician or in his absence, to the individual, over the telephone.

In a third embodiment of the invention, the detection of a herald signcauses one of a plurality of colored lights or similar indicators tolight, thus indicating to the patient what self-medication he shouldadminister to himself or whatever other steps he should take in theinability to immediately communicate with the center and his physician,or whenever immediate danger exists. Particularly, the detection of aheartbeat rate below a given value, detection of a heartbeat rate abovea given value or detection of a skipped heartbeat are three herald signswhich can cause different lights to be lit, in addition to the operationof an audio alarm.

Many other objects and purposes of the invention will become clear fromthe following detailed description of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a first embodiment ofthis invention, whereby the ECG waveform of an individual wearing theunit is transmitted to a central facility continuously, etc. when theunit detects a herald sign.

FIG. 2 shows a second embodiment of this invention.

FIG. 3 shows a normal ECG waveform.

FIG. 4 shows a third embodiment of this invention.

DETAILED DESCRIPTION OF THE DRAWINGS Reference is now made to FIG. 1which shows a first embodiment of this invention. In this embodiment,-anumber of individuals with established cardiac difficulties or who arecardiac prone are each equipped with a portable, self contained andpowered unit which monitors their ECG waveforms continuously andresponds to conditions which appear to be herald signs. in FIG. 1, threesuch units 20, 22 and 24 are diagrammatically illustrated.

As shown, unit 24, which is intended to be identical to units and 22,includes a power source 26 which may be a small nickel-cadmium or otherbattery and which supplies the energy requirements of unit 24. Ifdesired, provision may be made for visually or audibly indicating to thewearer when the battery is marginally depleted or the electrical systemis malfunctioning.

A conventional amplifier 28 of which many types are known detects theminute electrical signals produced by the electrodes connected to thebody and amplifies them to produce the conventional ECG waveform. Anormal ECG wave is shown in FIG. 3. The ECG waveform signal produced byamplifier 28 is passed to logic network 30 which then determines, bybuilt-in programming, if a condition exists which might be a heraldsign. For example, logic 30 may include a timing circuit which checksthe temporal separation between each R wave peak and the last R wavepeak and produces an alarm signal if the separation is less than a firstgiven time or greater than a second given time, thus detecting high andslow heartbeat rates as well as skipped beats. As discussed below, unit24 preferably includes a recorder 31.

Whenever logic 30 detects a herald sign, it produces a trigger signalwhich is passed to transmitter 32 which causes transmitter 32 totransmit, at an assigned frequency, the ECG waveform signal beingproduced by amplifier 28. The ECG information may be modulated onto thetransmission frequency or otherwise sent. While microwave or low RFsignals may be satisfactory in regions where there are few large steelstructures VHF signals are believed to be more satisfactory under allconditions based on present technology. Each of the units in the systemwill preferably be assigned a different frequency so that the source ofreceived signals can be quickly and reliably ascertained. The use of sixdigits to each multihertz cycle with multiplexing permits thesimultaneous transmission of large numbers of ECG signals from differentindividuals only at such times when a herald sign is detected.

The central facility 34 receives the signals transmitted by unit 24 and,more particularly, a receiver 36 detects the transmitted signals andconverts them to a frequency or form, such as AC current, suitable foruse by the digital computer 38 which is properly programmed to analyzethe ECG waveform and provide information as an output, including the ECGwaveform, useful to the expert, who is continuously on alert whensignalled.

Computer 38 analyzes the information received and, when warranted,triggers an output alarm 40 and provides an output on monitor orprint-out 42 for the human expert to study. The monitor may be anoscilloscopic monitor and/or print-out and the information providedpreferably includes the ECG waveforms received, the patientsidentification and the identification of the patients personalphysician.

The computer 38 also preferably permanently recordsthe received ECGwaveform on tape storage 45 which may be destroyed from time to time..lfdesired, computer 38 may at the same time transmit the ECG to anotherremote monitor 39 such as the office or bedside of the personalphysician and/or cardiac consultant of the person transmitting the ECGwaveforms.

The human expert studies the ECG on monitor 42 and/or monitor 39 and ifhe considers that the situation warrants precautions, he directs manualactivation of transmitter 44 after it is automatically set to thefrequency of the unit to be contacted by computer 38. The signalstransmitted for example by transmitter 44 are received by receiver 46which includes a filter tuned to the frequency assigned to unit 24. Ifthe signal as produced or passed by receiver 46 is at the assignedfrequency, a signal is produced or passed by receiver 46 which triggersalarm 48 which includes an audio alarm and which tells the personwearing unit 24 that he should contact his personal physician or, if heis unavailable, center 34 immediately. The transmitted signal receivedby receiver 46 can also be used to trigger other devices in unit 24. Forexample, in FIG. 1 a defibrillator is provided which can be triggered byfacility 34 upon detection of ventricular fibrillation. Differentcolored lights indicating varying causes and hence different courses ofaction can also be lit as discussed below. The human expert preferablyalerts the personal physician before or just after transmitter 44 isactivated.

One of the drawbacks of the above discussed embodiment is the difficultyin transmitting through all environments in which the wearer may findhimself including large buildings of steel and concrete. Even at VHFfrequencies transmission may be impaired or distorted with possiblefailure of the center to detect or receive herald signs, but atfrequencies between roughly 2-50 MHz this problem is believed minimized.

In a second embodiment of the invention shown in FIG. 2 this problem iseliminated by providing a continuous tape loop 50 or a solid statememory device in the portable unit which is triggered by logic 52 whenthe logic determines that a condition which is a herald sign exists. Asin the embodiment of FIG. 1, a conventional power supply 54 and ECGdetector 56 are provided.

When triggered, an erasable tape loop 50 or solid state memory device orother recorder, records the ECG waveform for some given time, e.g.,until the entire loop has been filled. If desired, tape loop 50 canrecord continuously and stop erasing only when a herald sign isdetected. However, it has been determined that the ECG signal after theevent occurs almost always indicates the nature of the problem and theevent. Accordingly, the greater simplicity in design and less powerconsumption of this approach suggests that recording will usually bedesirable only upon detection of a herald sign. Logic 52 also respondsto the detection of a condition which might be a herald sign byoperating an audio alarm 55 which alerts the patient, who has beeninstructed to go immediately to a telephone and call the centralfacility which as in FIG. 1 is equipped with a computer andaccessibility to a human expert for analyzing the recorded ECG waveform.Alarm 55 can also include lights or other indicators which further tellthe patient what actions should be taken. If desired, the patient can becontinuously coupled to the phone and his ECG continuously monitored bythe computer.

When the center has been reached, the tape is played and the informationpassed to the center via acoustic coupler 60 which is operated by manualcontrol 62 and the telephone lines. The computer at the central facilitythen receives the information andproduces an output as in FIG. 1 for thehuman expert to study. After the ECG has been completely transmitted,the unit wearer receives detailed instructions from the human expert asto what he should do.

Reference is now made to FIG. 4 which shows a further embodiment of theinvention of this application. In this embodiment, the ECG waveform isdetected by properly placed electrodes and an amplified signal fromamplifier 70 is applied to logic 72 which, like the other logic devicesdescribed above, detects one or more herald signs. In particular, logic72 is designed to detect when the heartbeat rate is less than a givenvalue, for example, about 54 beats per minute, greater than a secondvalue, for example, 120-130 beats per minute, or when a heartbeat hasbeen skipped. Many simple logic arrangements for detecting theseconditions should be apparent and these include arrangements fordetermining the time between adjacent R-wave peaks and for triggeringappropriate signals on different outputs when that spacing is greaterthan, or less than, preset values. A conventional power supply 74, whichmay also be of the type described above, supplies the power to logic 72as well as the other elements of the device.

Whenever a herald condition is detected an appropriate signal isproduced on line 76 which triggers an audio alarm 78 which the patientcan hear. A manual volume adjustment 80 is provided so that the volumecan be increased during sleep, or when the patient is under conditionswhere the audio alarm 78 might not otherwise be heard.

Further, logic 72 is provided with three or more additional outputs eachof which are connected to a separate indicator which is in thisembodiment a colored light. Thus when a low heartbeat rate is detected,a signal is produced on line 82 which causes line 84 to becomeilluminated and remain illuminated. Similarly, the detection of a highheartbeat rate causes an appropriate signal to be produced on line 86 tocause illumination of colored light 88. Further, the detection of askipped heartbeat produces a signal on line 90 which causes light 92 tobe lit. Each of the lights 84, 88 and 92 are preferably of differentcolors, for example, red, yellow and green.

Thus, the patient is not only warned that a herald sign has occurred, heis specifically informed as to the condition which caused the audioalarm 78 to operate. This is important since there are manycircumstances under which it is necessary for the patient to respond tothe detected condition. A low heart rate is particularly critical sincecompeting lower and mechanically inadequate rhythmic centers may escapewith resultant cardiac arrest and/or shock. The detection of a skippedbeat may also be important enough to justify some immediate action. Highheartbeat rates except ventricular tachycardia do not normally requireimmediate action unles ventricular fibrillation results, in which casethe patient will be unable to respond to the warning himself.

Accordingly, it is contemplated that with this embodiment, the patientwill be provided with appropriate drugs to use when the associated lightgoes on, when immediate communication with the physician is impossible.The drugs may be taken in any form. While the critical point for the lowrate is fairly constant, the point at which logic 72 should trigger awarning for a high heartbeat rate may vary from individual to individualand according to the activities of that individual. Accordingly, it isdesirable to be able to adjust the rate value which triggers logic 72and a suitable mechanism for accomplishing that purpose is shown in FIG.4. Normally, this adjustment will be unavailable to the patient but willbe made by the physician at the time that the individual is given theunit or subsequently when indicated.

While the patient can administer medicine to himself in response to thevarious alarm signals, it is contemplated that he will be instructed tocontact his physician or someone else whenever he receives an alarm.Further, it is contemplated that this type of unit can be used incombination with the transmitter unit or the recording device shown inFIGS. 1 and 2, and that logic 72 will be designed so as to be compatiblewith such other devices. The unit shown in FIG. 4 may then be usedinitially with those patients who are not thought to be extremelyserious. If later the patient's condition warrants it, the appropriaterecording mechanism and acoustical coupler or transmitter can be added.

Many changes and modifications in the above embodiment of the inventioncan, of course, be made without departing from the scope of theinvention and that scope is intended to be limited only by the scope ofthe appended claims.

What is claimed is:

1. An apparatus for detecting potentially dangerous herald signs in acardiac waveform of an individual comprising:

means for detecting the cardiac waveform and producing a signalrepresenting that waveform,

means for receiving said representing signal, producing a first outputsignal when the heartbeat rate is less than a first given ratev andproducing a second output signal when the heartbeat rate is greater thana second given rate,

means for receiving said first output signal and producing a light of afirst color to the individual that the rate has been determined to beless than said first rate,

means for receiving said second output signal and producing a light of asecond color different from said first warning signal and indicating tothe individual that the rate has been determined to be greater than saidsecond rate,

means for receiving said representing signal, said first output signaland said second output signal and for recording said representingwaveform for a given time after receipt of either said first output orsecond output signal,

means for transmitting the recorded signal, to a remote facility aftersaid herald sign is detected, and

means for receiving said first output signal and said second outputsignal and producing an audible noise whenever either said first colorlight or said second color light is produced.

2. An apparatus as in claim 1 including means for manually adjusting thevolume of said third warning signal.

3. An apparatus as in claim 1 wherein said transmitting means includesmeans for detachably coupling said transmitting means to a telephoneline.

4. An apparatus as in claim 1 wherein said receiving and first andsecond output signal means includes means for producing a third outputsignal when a heartbeat is skipped and including means for receivingsaid third output signal and producing a third warning signal indicatingto the individual that the heartbeat has been skipped.

5. An apparatus as in claim 1 including a housing containing all of saidmeans and adapted to be carried by said individual.

6. An apparatus for detecting and responding to herald signs in thecardiac waveform of an individual comprising:

means for detecting the cardiac waveform and producing a signalrepresenting that waveform, means for receiving and recording saidrepresenting signal, and

means for receiving said representing signal for detecting herald signsand for controlling said receiving and recording means so that saidreceiving and recording means preserves a portion of said representingsignal whenever a herald sign is detected, including means fortranslating said recorded representing signal into a radio signal andtransmitting said radio signal to a remote facility,

means for receiving a radio signal from said remote facility andproducing an alarm signal which is manifest to said individual.

7. An apparatus as in claim 6 wherein said receiving and producing meansincludes defibrillating means operable in response to a given signalfrom sai remote receiver.

8. A system for detecting and responding to herald signs in the cardiacwaveforms of individuals comprising:

' a central monitoring facility including computer means for receivingand analyzing a received signal, means for displaying the output of saidcomputer means, memory means for storing the output of the computer andmeans for transmitting the output of the computer to a remote location,and I a plurality of individual units each adapted to be carried with anindividual and each including,

means for detecting the cardiac waveform and producing a signalrepresenting that waveform, means for detecting a herald sign,

means for receiving and recording said representing signal for a giventime after a herald sign is detected, and

means for transmitting said recording to said central facility.

9. A method of detecting and responding to herald signs in the cardiacwaveforms of individuals in a system with a central monitoring facilityand a plurality of individual units each adapted to be carried with anindividual comprising the steps of:

detecting the cardiac waveform in each individual unit and producing asignal representing that waveform,

detecting a herald sign in each unit,

recording and retaining said representing signal in a unit for a giventime after a herald sign is detected in that unit, and transmitting saidrecording to said central facility after a herald sign is detected,analyzing said transmitted recording in said central facility andtransmitting information with respect to future actions to be taken fromsaid central facility back to the individual having a unit which hastransmitted said recording after detecting a herald sign.

10. A method of detecting and responding to herald signs in the cardiacwaveforms of individuals in a system with a central monitoring facilityand a plurality of individual units each adapted to be carried with anindividual comprising the steps of:

detecting the cardiac waveform in each individual unit and producing asignal representing that waveform,-

detecting a herald sign in each unit,

recording and retaining said representing signal in a unit for a giventime after a herald sign is detected in that unit, and I transmittingsaid recording to said central facility after a herald sign is detected,receiving and analyzing the transmitted signal in computer means at saidcentral facility, displaying the output of said computer means, storingthe computer output and transmitting the computer output to a remotelocation.

1. An apparatus for detecting potentially dangerous herald signs in acardiac waveform of an individual comprising: means for detecting thecardiac waveform and producing a signal representing that waveform,means for receiving said representing signal, producing a first outputsignal when the heartbeat rate is less than a first given rate andproducing a second output signal when the heartbeat rate is greater thana second given rate, means for receiving said first output signal andproducing a light of a first color to the individual that the rate hasbeen determined to be less than said first rate, means for receivingsaid second output signal and producing a light of a second colordifferent from said first warning signal and indicating to theindividual that the rate has been determined to be greater than saidsecond rate, means for receiving said representing signal, said firstoutput signal and said second output signal and for recording saidrepresenting waveform for a given time after receipt of either saidfirst output or second output signal, means for transmitting therecorded signal, to a remote facility after said herald sign isdetected, and means for receiving said first output signal and saidsecond output signal and producing an audible noise whenever either saidfirst color light or said second color light is produced.
 2. Anapparatus as in claim 1 including means for manually adjusting thevolume of said third warning signal.
 3. An apparatus as in claim 1wherein said transmitting means includes means for detachably couplingsaid transmitting means to a telephone line.
 4. An apparatus as in claim1 wherein said receiving and first and second output signal meansincludes means for producing a third output signal when a heartbeat isskipped and including means for receiving said third output signal andproducing a third warning signal indicating to the individual that theheartbeat has been skippeD.
 5. An apparatus as in claim 1 including ahousing containing all of said means and adapted to be carried by saidindividual.
 6. An apparatus for detecting and responding to herald signsin the cardiac waveform of an individual comprising: means for detectingthe cardiac waveform and producing a signal representing that waveform,means for receiving and recording said representing signal, and meansfor receiving said representing signal for detecting herald signs andfor controlling said receiving and recording means so that saidreceiving and recording means preserves a portion of said representingsignal whenever a herald sign is detected, including means fortranslating said recorded representing signal into a radio signal andtransmitting said radio signal to a remote facility, means for receivinga radio signal from said remote facility and producing an alarm signalwhich is manifest to said individual.
 7. An apparatus as in claim 6wherein said receiving and producing means includes defibrillating meansoperable in response to a given signal from said remote receiver.
 8. Asystem for detecting and responding to herald signs in the cardiacwaveforms of individuals comprising: a central monitoring facilityincluding computer means for receiving and analyzing a received signal,means for displaying the output of said computer means, memory means forstoring the output of the computer and means for transmitting the outputof the computer to a remote location, and a plurality of individualunits each adapted to be carried with an individual and each including,means for detecting the cardiac waveform and producing a signalrepresenting that waveform, means for detecting a herald sign, means forreceiving and recording said representing signal for a given time aftera herald sign is detected, and means for transmitting said recording tosaid central facility.
 9. A method of detecting and responding to heraldsigns in the cardiac waveforms of individuals in a system with a centralmonitoring facility and a plurality of individual units each adapted tobe carried with an individual comprising the steps of: detecting thecardiac waveform in each individual unit and producing a signalrepresenting that waveform, detecting a herald sign in each unit,recording and retaining said representing signal in a unit for a giventime after a herald sign is detected in that unit, and transmitting saidrecording to said central facility after a herald sign is detected,analyzing said transmitted recording in said central facility andtransmitting information with respect to future actions to be taken fromsaid central facility back to the individual having a unit which hastransmitted said recording after detecting a herald sign.
 10. A methodof detecting and responding to herald signs in the cardiac waveforms ofindividuals in a system with a central monitoring facility and aplurality of individual units each adapted to be carried with anindividual comprising the steps of: detecting the cardiac waveform ineach individual unit and producing a signal representing that waveform,detecting a herald sign in each unit, recording and retaining saidrepresenting signal in a unit for a given time after a herald sign isdetected in that unit, and transmitting said recording to said centralfacility after a herald sign is detected, receiving and analyzing thetransmitted signal in computer means at said central facility,displaying the output of said computer means, storing the computeroutput and transmitting the computer output to a remote location.